The first question is whether he has changed the natural water runoff. Natural water run-off after a heavy rain is not your neighbor's fault. You should look to your own homeownerâs insurance for water damage. If your neighbor changes the natural condition of his land so that it causes increased water runoff, he is responsible for the damage to your property. He can argue that the benefit to his land far outweighs the impact to your land and there is no practical way to prevent the run-off. However, the courts will not allow your land to be flooded by a change in the natural flow if there is a practical way to avoid it â like a drainage ditch or culvert. Be smart. If you are landscaping your property, and more water is going to runoff onto your neighbor's land, be a good neighbor and learn from the Carey Brothers how to make provisions for proper drainage.